Warn when additional test cases have been added.

We already had a warning when testcases have been re-ordered or removed,
but didn't catch the case where additional cases have been added to the
end.

Fixes DOMjudge#2765.

webapp/src/Controller/Jury/SubmissionController.php

@@ -378,6 +378,9 @@ public function viewAction(
                 ->getScalarResult();
 
             $cnt = 0;
+            if (count($judgingRunTestcaseIdsInOrder) !== count($runResults)) {
+                $sameTestcaseIds = false;
+            }
             foreach ($runResults as $runResult) {
                 /** @var Testcase $testcase */
                 $testcase = $runResult[0];